This invention relates to data recorder/reproducer devices, and particularly those of the type having a rotatable shaft for moving the transducing head or heads along the recording media, as in a disc recorder, particularly of the type using a thin, flexible disc and including one or more movable heads. More particularly still, the present invention relates to a unique lead screw drive for translating the head or heads of such a data recorder/reproducer device.
Various forms of data recorder/reproducer devices for disc media are presently available. Some of these devices store and reproduce information on thin, flexible discs. The discs for such recorders are typically made by coating both sides of a thin, "floppy," sheet of polymeric film or other plastic material with a magnetic oxide. The disc is then permanently enclosed within a protective, sleeve-like envelope within which the disc may be rotated. The recorder typically includes means for supporting and rotating one or more discs, and includes one or more heads or transducers movable across the disc for storage or retrieval purposes. An example of one such recorder may be found in commonly-owned U.S. Pat. No. 3,913,137 to Morgan, entitled TWIN FLEXIBLE DISC RECORDER WITH MOVABLE HEADS and issued on Oct. 14, l975.
As disclosed therein, this device includes a frame supporting a long worm shaft or lead screw, adapted for translating a pair of transducers or heads. The frame defines a pair of spaced, coaxial support points at which are disposed bearings. The ends of the lead screw are supported by the bearings and the lead screw is coupled to a drive motor or stepper motor through a flexible, bellows-type coupling. This lead screw drive forms the subject matter of commonly-owned U.S. Pat. application, Ser. No. 655,970, filed Feb. 6, 1976 and entitled DISC RECORDER WITH LEAD SCREW DRIVE. With this arrangement, the lead screw is supported independently of the stepper motor and the universal drive coupling is employed to compensate for alignment and position variations. Since the lead screw drive translates the input/output transducers of the recorder across the disc media, moving from track to track and stopping to accurately position the transducers at selected recording tracks, the alignment, positioning and accuracy of the lead screw drive are critical to proper operation, a fact made evident by considering that typical radial track density is on the order of 48 tracks per inch. Thus, it is extremely important that the lead screw not shift or change position or alignment with respect to the frame during operation. As a result, it is regarded by many to be necessary to support both ends of the lead screw independently of the stepper or drive motor to achieve such accuracy in positioning.